1. Technical Field
This invention relates generally to the delivery of vertical features that have been recently incorporated into North American analog and digital cellular/PCS standards. More specifically, the invention provides a method and apparatus for wireless communication systems to query mobile stations operating in analog mode as the need arises for the detailed capability information required to efficiently and reliably deliver these vertical features to those mobile stations. Also, the invention provides an additional method and apparatus for wireless communication systems to control the solicitation of the capability information using the overhead information. The ability to query mobile stations for capability information circumvents the need to configure, maintain, and transport this information around the network infrastructure as a mobile station roams between mobile serving areas.
2. Related Art
Wireless communication systems are well known in the art. In a typical wireless communication system, several base stations connected via a mobile switching center provide wireless communication infrastructure within a service area. Such combination of stationary base stations and the mobile switching center is often referred to as the “network.” Within the service area, each of the base stations provides wireless communication capability within a respective cell. Each cell may be further subdivided into one or more sectors. The base stations communicate with subscribing units operating within respective cells. The subscribing units may be hand held units, car mounted units or other units capable of communicating with the base stations. The mobile switching center routes communications between the base stations and the public switched telephone network and other mobile switching centers supporting other respective service areas. Thus, users of the subscribing units operating within the service area may communicate with users connected to the public switched telephone network as well as users of other subscribing units.
Wireless communication systems generally support standard operating protocols that specify the communication between subscriber units and base stations. Standard operating protocols include the Advanced Mobile Phone Service (AMPS) standards, the Narrowband Advanced Mobile Phone Service (NAMPS) standards, the Global Standard for Mobility (GSM), the Code Division Multiple Access (CDMA) standard and Time Division Multiple Access (TDMA) standards, among others. These standards are typically not compatible with one another. While some base stations and some subscribing units may support more than one standard operating protocol, at any given moment in time, a base station and a subscribing unit must communicate using the same protocol.
Further, variations exist within the operating protocols. The AMPS standard, for example, includes a number of differing standards, such as the IS-3, TIA/EIA 553, IS-88, IS-91, TIA/EIA 553-A, and IS-95 standards. In addition, a single standard may have different protocol revisions, such as the IS-95A and IS-95B protocol revisions. Thus, complexities arise even when the base station and subscribing units operate according the same standard but under differing protocol revisions. While the base station may support more than one protocol revision, the base station cannot always determine which protocol revisions the analog subscribing unit supports.
Recently, several vertical features have been incorporated into the North American analog cellular standards and the analog sections of dual mode cellular standards, for example the TIA/EIA 553-A and IS-91-A analog standards and the IS-95-A dual mode standard. Calling Line Identification (CLI), Message Waiting Notification (MWN), Short Message Services (SMS), and Priority Access and Channel Assignment (PACA) are among the vertical features recently incorporated into the standards cited.
The standards allow some vertical features to be implemented at the option of mobile station manufacturers. To further complicate matters, a second layer of options is also allowed. Although a mobile station manufacturer may choose to support an optional vertical feature, the standards often do not require the mobile to support all possible mechanisms for delivering that vertical feature to the mobile station. For example, SMS is an optional vertical feature in the IS-91-A standard. However, there are two mechanisms provided for delivering SMS to a mobile station operating in accordance with the IS-91-A standard: the Extended Protocol (EP) SMS message and the Alert With Info SMS message. If a mobile manufacturer chooses to support the IS-91-A SMS feature, it has the option of supporting the EP SMS message, the Alert With Info SMS message, or both messages. The same is true for the IS-91-A CLI and MWN features. The standard allows the CLI feature to be delivered using either the EP CLI message or the Alert With Info/Flash With Info messages. The MWN feature may be delivered using the EP Voice Mail message or the Message Waiting Order.
The variety of these vertical features and the variety of their delivery mechanisms have created implementation difficulties for analog operations of wireless mobile communication systems. To operate efficiently and reliably when one of these vertical features is to be delivered to a mobile station, the system is required to know, unambiguously, whether the mobile supports that vertical feature and the mechanism(s) by which the mobile accepts delivery of that feature. One technique to address this problem is to require the cellular service provider to record (e.g., datafill) detailed mobile station capability information in the subscriber's profile. This information would then be propagated throughout the cellular network wherever the subscriber roams to and obtains service. North American standards bodies have resisted the burden that this technique would place upon the cellular network and have declined to include such a capability in the relevant networking standards such as IS-41. Furthermore, cellular service providers prefer to maintain service level information (such as whether a customer has subscribed for SMS rather than the specific option(s) of the air-interface protocol that each mobile manufacturer has chosen to support delivery of that service. It is clear that the industry expects the analog communication system serving the subscriber to ascertain, as needed, the vertical features and delivery mechanisms supported by the mobile station.
Historically, the 2-bit Mobile Protocol Capability Indicator (MPCI) field that a mobile station reports to an analog communication system when it registers with the system or originates a call was sufficient for the analog communication system to determine how to provide service to the mobile station. A mobile station sets the MPCI to ‘00’ to report as an analog mobile (any one of IS-3, TIA/EIA-553, IS-88, IS-91, TIA-EIA-553-A, and IS-91-A), sets the MPCI to ‘01’ to report as an IS-54-B mobile (TDMA dual mode), sets the MPCI to ‘10’ to report as any IS-95 mobile (CDMA dual mode), and sets the MPCI to ‘11’ to report as any IS-136 mobile (TDMA Digital Control Channel dual mode). As such, the MPCI is inadequate to distinguish between analog mobile standards and standard revisions, much less standard optionality nuances.
When the more modern North American digital standards were being developed (i.e. IS136, IS95) the standards bodies recognized the limitation of the MPCI and incorporated extensive facilities in the digital standards to: 1) communicate the capability of the digital communication system to the digital mobile stations; and 2) to request the mobile station for a detailed list of capabilities. Analog communication systems may serve analog mobile stations or dual-mode digital/analog mobile stations operating in analog mode. Unfortunately, the ability for analog mobile communication systems to discern capability information beyond MPCI has not kept pace with the proliferation of standards, standard revisions, and vertical feature optionality.
Thus, there is a need in the art for a wireless communication system that provides support for subscribing units operating in its service area, each of which may support differing standards, protocol revisions and extended services. Such a system must efficiently utilize available bandwidth within the service area to maximize capacity and minimize traffic.